docs: def get_amount_normal(self, billing_cycle):
          """Get the amount due on the given billing cycle
  
          For regular recurring costs this is simply `fixed_amount`. For
          one-off costs this is the portion of `fixed_amount` for the given
          billing_cycle.
          """
          if self.is_one_off():
              billing_cycle_number = self._get_billing_cycle_number(billing_cycle)
  
              if billing_cycle_number > self.total_billing_cycles:
                  # A future billing cycle after this one has ended
                  return Decimal('0')
              else:
                  # This is a current cycle. Split the amount into
                  # equal parts then return the part for this cycle
                  splits = ratio_split(
                      amount=self.fixed_amount,
                      ratios=[Decimal('1')] * self.total_billing_cycles,
                  )
                  return splits[billing_cycle_number - 1]
          else:
              # This is a none-one-off recurring cost, so the logic is simple
              return self.fixed_amount